1. Field of the Invention
This invention relates to method and apparatus for cleaning a hollow air duct and more particularly, to new and novel method and apparatus for drawing an air emitting cleaning nozzle and a high pressure air supply hose coupled thereto through a heating, ventilating and air conditioning duct.
2. Description of the Prior Art and Objects
Commercial and industrial buildings typically include heating, ventilating and air conditioning ducts, commonly referred to as HVAC ducts. Some of these ducts are extremely large. Heretofore, one prior art method of cleaning the ducts included having someone walk inside the duct and manually scrape or dislodge the material. Such manually dislodged dirt would be picked up with a vacuum sweeper or a broom and a dust pan. Such activity is now prohibited by the occupational safety laws which will not allow anyone to walk in a confined area without a portable sniffer to check the air. Accordingly, it is an object of the present invention to provide a new and novel method and apparatus for cleaning a HVAC duct which will be more efficient and less expensive than the prior art method and apparatus.
Apparatus has been provided heretofore for cleaning heating, ventilating and air conditioning ducts, sometimes referred to as HVAC ducts, such as that disclosed in U.S. Pat. No. 5,003,998 issued to Donald H. Collett on Apr. 2, 1991. The aforementioned Collett patent discloses a so-called skip ball which is mounted on the end of a highly pressurized air supply hose that is disposed in the air duct to be cleaned via a hole cut in the side wall of the air duct. The air being emitted by the skip ball is, in some instances, as disclosed in the Collett patent, emitted at an inclined angle relative to the axis of the hose and the path of travel of the skip ball and the hose. The hose is pushed downstream to move the skip ball downstream. In the Collett patent, forwardly outwardly diverging air outlet passages are provided in the skip ball for directing high velocity cleaning air at an angle relative to the duct side wall. The air being emitted tends to retard the forward downstream progress of the skip ball in the duct.
Another prior art skip ball utilizes air emitting passages which are reversely angularly disposed to aid the propulsion of the skip ball through the duct. Due to the weight of the prior art ball and hose, the ball which, with the exception of the air supply hose, is unsupported, will sometimes engage the bottom wall of the duct and catch on any inwardly extending projections, such as fasteners, that frequently appear on the inside of an HVAC duct. This prior art system has further limitations because the cleaning air being outwardly emitted in the direction of the travel of the hose will tend to cause the ball to move sideways and catch on obstructions and extending inwardly into the duct. Such prior art systems and techniques are effective in only moving the skip ball through a limited distance such, as for example, 20-30 feet. Due to the extreme length of such HVAC ducts, the manual feeding of the high pressure air hose through the duct is ineffective. Thereafter, apertures must be cut at regular intervals in the duct and the nozzle and hose retracted from an upstream aperture and reinserted through successive downstream apertures and the operation repeated.
Accordingly, it is an object of the present invention to provide new and novel method and apparatus for cleaning HVAC ducts which will draw a high velocity air emitting nozzle downstream through a substantially greater distance than that of the prior art systems.
It is another object of the present invention to provide method and apparatus of the type described for supporting a high velocity air cleaning nozzle in spaced relation with the interior wall of the duct and concurrently moving the nozzle downstream.
Although the skip balls, such as that in the aforementioned U.S. Pat. No. 5,003,998, are able, under limited circumstances,to dislodge some of the dirt material through a limited portion of the duct, there will be insufficient vacuum forces to move the dislodged dirt particles. Accordingly, it is another object of the present invention to provide new and novel method and apparatus for cleaning HVAC ducts which will draw away the dislodged material with higher velocity streams of air in the duct than otherwise exists within the duct.
It is another object of the present invention to provide method and apparatus for cleaning heating, ventilating and air conditioning ducts which includes new and novel apparatus for drawing a high pressure air emitting member through the duct.
Typically, heating, ventilating and air conditioning systems include an air moving fan or blower which forces air through ducts in a direction away from the fan and simultaneously creates a vacuum to draw return air through a return duct to thus, circulate air throughout a building. It has been found that additional vacuum forces can be temporarily imposed in the duct by coupling a vacuum creating unit to a downstream portion of an air supply duct coupled to a portable fan.
The apparatus constructed according to the present invention contemplates a "parachute" or "umbrella" type draught member which is disposed in the HVAC duct to be drawn by the vacuum forces in a downstream path of travel. The draught member comprises an expansible and contractible sheet of fabric which is coupled to high pressure, air emitting nozzle via a plurality of coupling lines which are coupled to perimetrically spaced portions of the sheet of fabric. Accordingly, it is another object of the present invention to provide method and apparatus for cleaning air ducts of the type described including a draught member which is disposed in the duct and is coupled to the air emitting member for drawing the air emitting member downstream.
It has been found, according to the present invention, that if the "parachute" is smaller than the duct, the parachute becomes unstable and laterally whips back and forth as it is moved downstream. This is occasioned because the heating, ventilating and air conditioning air passing through the duct must now pass through a reduced cross sectional area in the gap between the edge of the parachute and the adjacent confronting portion of the duct being cleaned. This, in essence, creates a venturi effect which draws the heating, ventilating and air conditioning air to pass through the restricted passage at a substantially high velocity to more effectively draw the dislodged particles downstream. Accordingly, it is another object of the present invention to provide method and apparatus of the type described which will block a portion, but not all, of an HVAC duct to create a high velocity air stream in a portion of the HVAC duct to funnel the air passing through the duct through a reduced cross sectional area and thereby increase the velocity of air passing therethrough and more effectively aid the movement of the dislodged dirt downstream.
Applicant's prior U.S. Pat. No. 4,141,753 issued on Feb. 27, 1979 to Bruce W. Creed, the inventor herein, discloses method and apparatus for the in-situ internal cleaning of a hollow suction duct which pulls a liquid emitting member through the duct. Although Applicant's prior art patent discloses the use of a parachute type device, this prior art parachute was not disposed in the duct with the liquid emitting member and did not directly draw the liquid emitting member through the duct but rather was utilized to draw a light weight wire through the duct which, in turn, was coupled to a heavier cable which, in turn, was coupled to the relatively heavy liquid emitting nozzle. Accordingly, it is another object of the present invention to provide new and novel method and apparatus of the type described for cleaning air ducts with high pressure air.
In Applicant's prior art patented system, the parachute substantially closed the entire duct. Accordingly, it is another object of the present invention to provide method and apparatus of the type described which includes an expansible and contractible draught member which will close a substantial portion, but not all of the duct, to create a low pressure, high velocity zone between a perimetrical portion of the expansible and contractible member and the adjacent confronting portion of the duct to pass the heating, ventilating and air conditioning air therethrough with a higher velocity than velocity of the air otherwise passing through the duct.
It is another object of the present invention to provide method and apparatus of the type described for cleaning a HVAC duct and which will alternately form low pressure zones between perimetrically spaced portions of the expansible and contractible member and adjacent confronting portions of the duct to cause the expansible and contractible member to move in a to-and-fro transverse path as it is moved downstream.
The present invention also contemplates the use of an abrasive member along the perimetrical edge of the sheet of fabric which will wipe a portion of the duct as it is moved to-and-fro and as it moves downstream. Accordingly, it is another object of the present invention to provide a band of abrasive material along the outer perimetrical edge of an expansible and contractible draught member for drawing a high pressure, air emitting nozzle downstream.
The air being emitted by the nozzle in the aforementioned U.S. Pat. No. 5,003,998 impinges on the wall with a glancing blow. Such a blow will not have maximum impact on the dirt to be dislodged. Accordingly, it is another object of the present invention to provide method and apparatus for cleaning heating, air conditioning and ventilating ducts which includes an air nozzle which will emit pressurized air in a stream perpendicular, or normal, to the air duct and perpendicular to the axis of the duct.
It is another object of the present invention to provide a method and apparatus for cleaning hollow HVAC ducts which will more effectively remove particles of dirt that inadvertently accumulates on the inside of the duct.
It is a further object of the present invention to provide method and apparatus of the type described which includes an expansible and contractible member that will, in expanded condition, close a majority of the duct to increase the velocity of the air in a gap which is disposed between the perimetrical edge of the expansible contractible member on the confronting portion of the duct to draw debris downstream therewith to clean the duct.
Various other vent and duct cleaning systems are disclosed in the following cited prior art patents which are of interest but do not disclose Applicant's construction:
______________________________________ U.S. Pat. No.: PATENTEE DATE OF ISSUE ______________________________________ 5,580,393 Lawther December 3, 1996 5,364,473 Van Der Does November 15, 1994 5,003,998 Collett April 2, 1991 4,792,363 Franklin, Jr. et al December 20, 1988 4,011,100 Ross March 8, 1977 3,091,433 Riley, et al May 28, 1963 2,794,197 Crane June 4, 1957 2,508,659 Brown May 23, 1950 ______________________________________
Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds.